Genetic determinants of variability in warfarin response after the dose-titration phase

Quality of Life of Patients Receiving Warfarin Therapy at a Tertiary Care Centre in Indonesia Using DASS (Duke Anticoagulation Satisfaction Scale)

Purpose

This study aimed to examine the quality of life of patients receiving warfarin therapy at Dr. Hasan Sadikin Central General Hospital, and its relationship with demographic factors.

Patients and Methods

The procedures started with the submission of a study permit, followed by validation of the Duke Anticoagulation Satisfaction Scale (DASS) questionnaire. In addition, the validated questionnaire was completed by the participants, and significant variables were analyzed using the chi-square method for multivariate analysis.

Results

The results showed that the questionnaire was valid and could be used for further analyses. Among the 88 selected participants, 52 and 36 had scoring categories <56.266 and 56.266 ≤ x ≤ 143.734, respectively, with no patients having a scoring category > 143.734. In addition, participants with low education and aged ≥ 52 years were 4.916 and 3.161 times more at risk of having quality of life score of 56.266 ≤ x ≤ 143.734, respectively. Based on the results, the average quality of life score of patients was 59.66. Participants with low educational levels and those aged ≥ 52 years were at a higher risk of having quality of life score of 56.266 ≤ x ≤ 143.734.

Conclusion

In summary, a lower quality of life score was linked to increased comfort and satisfaction among patients receiving warfarin treatment. Additionally, these patients experienced fewer feelings of limitations and inconveniences related to their treatment plans.

Time in therapeutic range is lower in women than in men and is not explained by differences in age or comorbidity

BACKGROUND

Time in therapeutic range (TTR) measures the stability of the international normalized ratio in patients on vitamin K antagonists (VKA). Low values are associated with poor outcomes. Women were shown to have lower TTR than men, but the causes are poorly defined. It was suggested that women on VKA are older and more morbid than men, and this could affect the stability of anticoagulation. We aimed to identify variables that affect TTR differently in women and men.

MATERIALS AND METHODS

This is a retrospective study in patients referred to a University hospital anticoagulant clinic. Age, sex, comorbidities, number of daily medications, indication and type of anticoagulant, weekly dosage and distribution, were derived from electronic records. Differences by sex and regression analysis to identify significant modulators of TTR were computed.

RESULTS

1182 women and 1281 men on VKA were studied. Women were older than men (81.5 yrs. ± 11.2 vs 78.4 yrs. ± 12.2), and had lower TTR (65% ± 20.3 vs 69% ± 19.8). Comorbidity was similar between sexes and negatively affected TTR in both. Mechanical valves as an indication to anticoagulation and acenocoumarol as an anticoagulant as opposed to warfarin had a strong negative influence on TTR, while age increased TTR. Being a man rather than a woman afforded more than three TTR points. Number of medications and average anticoagulant dose were equal between sexes.

DISCUSSION

Women have a lower TTR than men, on average below the safety threshold. They were indeed older, but age positively influenced TTR. Since women and men were equally comorbid, neither age nor disease explains differences in TTR. None of the other variables included in the study could explain the gender gap in TTR. Since women are at increased risk of cardioembolic stroke in atrial fibrillation, an effort at defining other causes for the observed differences, closer monitoring and switching to direct anticoagulants whenever possible is warranted.

Impact of CYP2C9-Interacting Drugs on Warfarin Pharmacogenomics

Precise dosing of warfarin is important to achieve therapeutic benefit without adverse effects. Pharmacogenomics explains some interindividual variability in warfarin response, but less attention has been paid to drug‐drug interactions in the context of genetic factors. We investigated retrospectively the combined effects of cytochrome P450 (CYP)2C9 and vitamin K epoxide reductase complex (VKORC)1 genotypes and concurrent exposure to CYP2C9‐interacting drugs on long‐term measures of warfarin anticoagulation. Study participants predicted to be sensitive responders to warfarin based on CYP2C9 and VKORC1 genotypes, had significantly greater international normalized ratio (INR) variability over time. Participants who were concurrently taking CYP2C9‐interacting drugs were found to have greater INR variability and lesser time in therapeutic range. The associations of INR variability with genotype were driven by the subgroup not exposed to interacting drugs, whereas the effect of interacting drug exposure was driven by the subgroup categorized as normal responders. Our findings emphasize the importance of considering drug interactions in pharmacogenomic studies.

GGCX-Associated Phenotypes: An Overview in Search of Genotype-Phenotype Correlations

Gamma-carboxylation, performed by gamma-glutamyl carboxylase (GGCX), is an enzymatic process essential for activating vitamin K-dependent proteins (VKDP) with important functions in various biological processes. Mutations in the encoding GGCX gene are associated with multiple phenotypes, amongst which vitamin K-dependent coagulation factor deficiency (VKCFD1) is best known. Other patients have skin, eye, heart or bone manifestations. As genotype–phenotype correlations were never described, literature was systematically reviewed in search of patients with at least one GGCX mutation with a phenotypic description, resulting in a case series of 47 patients. Though this number was too low for statistically valid correlations—a frequent problem in orphan diseases—we demonstrate the crucial role of the horizontally transferred transmembrane domain in developing cardiac and bone manifestations. Moreover, natural history suggests ageing as the principal determinant to develop skin and eye symptoms. VKCFD1 symptoms seemed more severe in patients with both mutations in the same protein domain, though this could not be linked to a more perturbed coagulation factor function. Finally, distinct GGCX functional domains might be dedicated to carboxylation of very specific VKDP. In conclusion, this systematic review suggests that there indeed may be genotype–phenotype correlations for GGCX-related phenotypes, which can guide patient counseling and management.